HAVING large families should be frowned upon as an environmental misdemeanour
in the same way as frequent long-haul flights, driving a big car and failing
to reuse plastic bags, says a report to be published today by a green
think tank.

The paper by the Optimum Population Trust will say that if couples had
two children instead of three they could cut their family's carbon dioxide
output by the equivalent of 620 return flights a year between London and
New York.

John Guillebaud, co-chairman of OPT and emeritus professor of family
planning at University College London, said: "The effect on the planet
of having one child less is an order of magnitude greater than all these
other things we might do, such as switching off lights.

"The greatest thing anyone in Britain could do to help the future
of the planet would be to have one less child."

In his latest comments, the academic says that when couples are planning
a family they should be encouraged to think about the environmental consequences.

"The decision to have children should be seen as a very big one
and one that should take the environment into account," he added.

Professor Guillebaud says that, as a general guideline, couples should
produce no more than two offspring.

The world's population is expected to increase by 2.5 billion to 9.2
billion by 2050. Almost all the growth will take place in developing countries.

The population of developed nations is expected to remain unchanged and
would have declined but for migration.

The British fertility rate is 1.7. The EU average is 1.5. Despite this,
Professor Guillebaud says rich countries should be the most concerned
about family size as their children have higher per capita carbon dioxide
emissions.